Beating the Bushes Takes On New Meaning After Caterpillar Crawl, Lecture by the Effusive Dr. David L. Wagner

That’s how Dr. David L. Wagner, Assistant Professor of Ecology and Evolutionary Biology at the University of Connecticutt, began his talk Monday evening at the Austin Butterfly Forum. His audience of about 70 would be hard pressed to disagree after watching his entertaining and educational presentation.

Apart from their aesthetic contribution of morphing into the lilting butterflies we know and love, caterpillars are the “fabric that tethers the terrestrial communities” that keeps our forests and wildscapes whole, says Dr. Wagner. They’re also “the hamburger of the animal world.”

Grizzly bears in Yellowstone Park were observed consuming 20,-30,000 moths per day and the average robin has been known to eat 165 caterpillars in a single 24-hour stretch–more than twice its own bodymass. And the bats that emerge from the Austin’s Congress Avenue bridge? The flying mammals consume 10-20,000 insects nightly, “mostly moths,” says Dr. Wagner. Where would all these creatures be without caterpillars?

Birdwatchers are well aware of the consequence of caterpillars. They are the preferred grub of many songbirds. Dr. Wagner pointed out that caterpillar enthusiasts often start out as birders since effective birdwatching leads one to track the food source: caterpillars.

Caterpillars are also pollinators and responsible for the silk shirts and sheets we enjoy (thank you, silk moth!). Some species are the janitors of the wild, eating and cleaning up dead leaf matter. One of the lesser known imports of caterpillars is how they play a big-but-indirect role in our daily lives by exerting a “chronic force” on plants to evolve defense mechanisms to discourage being consumed by them.

“Plants are immobile. Caterpillars are omnipresent,” says Dr. Wagner. Plants have had to adapt to that. As a result, plants developed strong, often distasteful flavors like caffeine, latex and capsaicin to deter their consumption.

Coffee, tea, latex, aspirin, the tannins in red wine, cinnamon, pepper, and many other spices all result from plants’ reaction to caterpillars. “In a roundabout way, life would be considerably less rich and less interesting (and much less flavorful) without caterpillars,” said Dr. Wagner.

Dr. Wagner showed dozens of amazing and entertaining slides of caterpillars in various contortions and camouflage–posing as sticks, pretending to be flower buds–but the biggest laugh came when he described a peculiar habit of a particular skipper, a cute yellow-and-brown caterpillar that morphs into a lovely brown butterfly.

The silver spotted skipper, not uncommon in San Antonio and Austin, apparently practices the habit of “ballistic defecation”–shooting its excrement up to 153 centimeters from its body. The trick throws off predators by spreading its scent far and wide.Sunday morning a handful of Austin Butterfly Forum members were treated to an entertaining walk in the woods at the Barton Creek Greenbelt in Austin. Grabbing our “beating sheet” we tackled the dry riverbed, discovering myriad insects, but not a huge haul of caterpillars, thanks to the drought. For a proper demo of bush- beating technique, see the video, above.

Dr. Wagner recommends carrying a magnifying glass or lens to better observe the fascinating creatures. “Caterpillars are little mysteries. Much of the time you are not sure how they will turn out,” he says.